Process for nitrating sucrose



Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE Joseph A. Wyler,Allentown, Pa., assignor to Trojan Powder Company, Allentown, Pa.

No Drawing. Application September 28, 1936, Serial N0. 102,979

7 Claims.

My invention relates to a process for the nitration of carbohydrates andmore particularly relates to the nitration of sucrose. My invention has,as its principal object the providing of new and improved methods ofobtaining crystalline sucrose octanitrate, and among other objects of myinvention is the providing of methods for completely nitrating sugar tosugar octanitrate.

In my co-pending application S. N. 27,049 filed June 17, 1935, isdisclosed a process for nitrating carbohydrates in the presence ofnitrated esters of hydroxy aliphatic carbo-xylic acids.

As examples of suitable esters of hydroxy aliphatic carboxylic acids,mention was made of ethyl lactate, butyl lactate, ethyl glycollate, etc.

and examples were given to show how these may be used in order to eifectthe nitration of sucrose to the octanitrate.

I have made the discovery that the addition of certain agents to theesters of hydroxy aliphatic carboxylic acids produces mixtures which,when used in place of the esters of hydroxy aliphatic carboxylic acidsthemselves, possess certain properties and advantages not possessed byeither ingredient alone. These advantages and properties will bedescribed below.

Sucrose octanitrate is readily soluble in nitrated ethyl lactate,nitrated methyl lactate, nitrated ethyl glycollate, nitrated butyllactate, etc. The

Y degree of solubility of sucrose octanitrate varies with each solvent.Also, the viscosity of the solutions of sucrose octanitrate variesaccording to the particular solvent used. Consequently each solvent,when used in the nitration, has its own distinctive eifect upon thephysical condition of the product of nitration, that is, the product ofthe nitration may vary from a liquid to a pasty or granular masscomposed of crystals, depending upon the hydroxy acid ester used. Thus,for example, nitrated butyl lactate is preferred over nitrated ethyllactate if the product desired is to be a crystalline one.

Although such factors as solubility and viscosity of sucrose octanitratein these nitrated hydroxy acid esters have a significant bearing uponthe modus operandi of my process of nitration these are not the soledeterminant factors. Such other factors as super cooling of the sucroseoctanitrate when dissolved in a solvent, delayed crystallization of thesucrose octanitrate even after it has separated from its solvent,solubility of the mixed acid in the liquid nitration products, and otherfactors, the exact nature of which are unknown, have a very importanteffect upon the success of my process.

I have discovered that the addition of one or more members of the groupconsisting of compounds having the formula CnH2n+1NO3, where n equalsone to five, compounds having the formula CnH2n+2-mC1m, where 1:. equalsone to five and m equals one to eight, and dichlorethylether, to anester or a plurality of esters of hydroxy aliphatic carboxylic acidsproduces mixtures of usefulness in the nitration of sugar to sucroseoctanitrate, and that these mixtures possess unusual and distinctiveproperties, which properties are not to be expected from a knowledge ofthe properties of the individual members of a given mixture. Forinstance, if nitrated ethyl lactate itself is used with sucrose with amixed acid of say 60% nitric acid and 40% sulfuric acid essentially asdescribed in examples below, the resulting product will contain nocrystalline sucrose octanitrate or merely a very insignificant amount,even though analysis will show the sugar to be nitrated to sucroseoctanitrate.

Similarly, if carbon tetrachloride be used alone with sucrose, theresulting product will not be crystalline.

In each case a viscous emulsion, gum or plastic mass results, withoutthe separation of even an appreciable amount of crystalline sucroseoctanitrate, and this occurs even when the solubility relationships aresuch that the sucrose octanitrate should separate as crystals.

If now, we make a mixture consisting of say 60% by weight of ethyllactate and 40% carbon tetrachloride and use this with sucrose inessentially the same manner, an entirely different and new result isobtained. The product, sucrose octanitrate, begins to separate duringthe nitration in the form of plates and continues to do so throughoutthe further addition of the sugar and thereafter, for about one hour.The product thus gotten is crystalline and, due to the stirring, it isin the form of agglomerated particles varying in size from minute platesto pea-sized aggregates. The product is readily filterable.

Similarly, if we nitrate sugar in the presence of an aliphatic nitratesuch as, for example, methyl nitrate, in essentially the same manner asin examples below, liquid or plastic products result. I-Iowever, if weuse a mixture of say 70% nitrated ethyl lactate and 30% methyl nitratein place of the methyl nitrate alone, the unexpected result of sucroseoctanitrate separating in the form of crystals is obtained.

As mentioned above, when it is desired to make sucrose octanitrate inthe crystalline form, as a product of the nitration, I prefer to usebutyl LED lactate instead of ethyl lactate. However, mixtures of eitherof these with carbon tetrachloride or methyl nitrate or ethyl nitrate orthe like are still more desirable.

In order to more fully point out the function performed by my mixtures,I wish to emphasize that the nitrated hydroxy acid esters used in myprocess cooperate with the other agents used so as to effect a morecomplete separation of the sucrose octanitrate as crystals, and in doingthis cause a further improvement in the nitration process itself, inthat the incompletely nitrated sugar is more thoroughly exposed to theaction of the nitrating acid. The separation of the sucrose octanitrateas a crystalline product prevents the formation of a gummy protectivelayer around the sugar as it is fed to the nitrator and thus causes animprovement in the yield. If thesugar nitrate did not separate asdiscrete particles an imperfect nitration would result, as is the casewhen sugar and glycerine are nitrated in accordance with presentcommercial practice, wherein the yields are relatively low and whereinthe product is mainly the heptanitrate and not the octanitrate.

As illustrations of my process, the following embodiments of myinvention are given.

EXAMPLE No. 1

Nitration of sucrose in the presence of nitrated butyl lactate andcarbon tetrachloride 1351 parts of a mixed acid consisting of 57.8%nitric acid, 0.3% N203, 2.5% water and 39.4% sulfuric acid (by weight)are placed in a suitable nitrator and cooled to below 10 C. To thiscooled mixed acid add, with stirring, 130 parts of a mixture consistingof 60% by weight of nitrated butyl lactate and 40% carbon tetrachlorideand then 265 parts granulated sugar (dry), keeping the temperature below10 C. preferably at about C. When about half of the sugar has been addedthe separation of crystals of sucrose octanitrate will usally beobservable. After all the sugar has been added, the mixture is stirredfor about one hour additional, when the charge in the nitrator isallowed to flow to a separator. The

' sucrose octanitrate floats and, after draining away the acid layerunderneath, the sucrose octanitrate is drowned in a relatively largevolume of water. The drained acid is'readily recovered. The diluted acidmay or may not be recovered, depending upon costs, etc.

The sucrose octanitrate is filtered, washed with water, then with adilute alkali, as for example, 2% sodium bicarbonate or 2% ammoniasolution, and then again with water. The wet cake may then be furtherpurified by washing with cold ethyl alcohol or propyl alcohol, or methylalcohol, or butyl alcohol or amyl alcohol to dissolve out the solubleimpurities.

The yield of sucrose octanitrate is about 517 parts or 95% of theory.

EXAMPLE No. 2 V

Nitration of sucrose in the presence of nitrated butyl lactate andtetrachlorethane 675 parts, by weight, of a mixed acid consisting of 60%nitric acid and 40% sulfuric acid are placed in a suitable nitrator andcooled below C. To this cooled mixed acid, add with stirring 65 parts ofa mixture consisting of 70% nitrated butyl lactate and 30%tetrachlorethane and then 150 parts of sugar, keeping the temperaturebelow 10 C.

phatic carboxylic acids are liquids.

EXAMPLE No. 3

Nitratz'on' of sucrose in the presence of nitrated butylZactate+nitrated ethyl lactate+ethyl nitrate Using 65 parts by weight ofa mixture consist ing of Parts by weight Nitrated butyl lactate 25Nitrated ethyl lactate 26 Ethyl nitrate '14 and proceeding as in ExampleNo. 2 with the substitution of this mixture for the nitrated butyllactate-tetrachlorethane mixture, gave a yield of crystalline sucroseoctanitrate of 260 parts.

EXAMPLE No. 4-.

Nitration of sucrose in the presence of nitrated butyllactate-i-nz'trated ethyl lactate+butyl nitrate Using 65 parts by weightof a mixture consisting of:

Parts by weight Nitrated butyl lactate 39 Nitrated ethyl lactate 13Butyl nitrate 13 and proceeding as in Example No. 2 with thesubstitution of this mixture for the nitrated butyllactate-tetrachlorethane mixture, gave a yield of crystalline sucroseoctanitrate of 2'70 parts.

EXAMPLE N0. 5

Nitration of sucrose in the presence of nitrated butyl lactate+amylnitrate Using 65 parts by weight of a mixture consisting-of:

Parts by weight Nitrated butyl lactate 45 n-Amyl nitrate and proceedingas in Example No. 2 with the substitution of the above mixture for thenitrated butyl lactate-tetrachlorethane mixture gave a yield ofcrystalline sucrose octanitrate of 273 parts.

It should be noted that these examples are given merely by way ofillustration, and that variations in proportions of ingredients,temperatures, time of nitration, etc. may be made without departing fromthe spirit of this invention. Also, I may vary the manner of utilizationof the conitrating liquid, that is, I may first mix the alcohol and thehydroxy acid ester and then run these into the nitrator containing themixed acid. I may nitrate these individually and then run the nitratedproducts into the mixed acid to be'used in nitrating the sugar; or, Imay carry out this preliminary preparation of the nitrating mixture inany manner suitable for my needs.

It is important to note that although in the specific examples given,the materials used as addition agents to the esters of the hydroxy all-The use of the gaseous or the solid members requires no significantchange in the operations. The gaseous members are passed into the estersof the hydroxy aliphatic acids either before or during the nitra-' tionoperation itself. The solid members are usually dissolved in the estersof the hydroxy aliphatic carboxylic acids before these esters are addedto the nitrating bath.

Furthermore, it will be noted that in my examples I have mentioned onlythe lactic acid esters, but I wish to make it clear that the glycollicacid esters are the full equivalents of the lactic acid esters and maybe used interchangeably or in admixture therewith in my process.

Also, I wish to emphasize that compounds of the general formulaCnH2n+lNO3 where n equals one to five, and compounds of the generalformula C1LH21L+2mC1m, where n equals one to five and m equals one toeight, are the full equivalents of the specific members such as methylnitrate, ethyl nitrate, amyl nitrate, butyl nitrate, carbontetrachloride, tetrachlorethane and dichlorethyl-ether mentioned in theexamples above. Hence such substances as isopropyl nitrate, secondarybutyl nitrate, isobutyl nitrate, tertiary butyl nitrate, isoamylnitrate, etc. which correspond to the general formu a of CnH2n+1NO3given above as well as such substances as monoand dichlormethane, mono-,di-, tri-, pentaand hexachlorethane, mono-, di-, tri-, tetra-, penta-,hexa-, hepta-, and octa chlorides of propane, butane and pentane, whichcorrespond to the general formula of CnH2n+2mC1m given above, are to beconsidered as the equivalents of the members actually given in thespecific examples.

As many modifications may be made in the practice of this invention,without departing from the scope of the disclosures as herein made, nolimitations should be placed upon my invention, except as indicated inthe appended claims.

I claim:

1. The process of nitration which comprises nitrating sucrose in thepresence of a mixture consisting predominantly of an alkyl ester of amono hydroxy aliphatic carboxylic acid, said alkyl group containing notmore than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform.

2. The process of nitration which comprises nitrating sucrose in thepresence of a mixture consisting predominantly of a nitrated alkyl esterof a mono hydroxy aliphatic carboxylic acid, said alkyl group containingnot more than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform.

3. The process of nitration which comprises nitrating sucrose in thepresence of a mixture consisting predominantly of an alkyl ester of amono hydroxy aliphatic carboxylic acid, said alkyl group containing notmore than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform.

4. The process of nitration which comprises nitrating sucrose in thepresence of a mixture consisting predominantly of an alkyl ester of amono hydroxy aliphatic carboxylic acid, said alkyl group containing notmore than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform at a temperature less than 10 C.

5. The process of nitrating sucrose which comprises adding sucrose to anitration bath comprising sulphuric acid, nitric acid, an alkyl ester ofa mono hydroxy aliphatic carboxylic acid, said alkyl group containingnot more than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform, the proportion of alkyl ester of monohydroxyaliphatic carboxylic acid present in the mixture being greater than thatof any member or combination of members of aforesaid group, present inthe mixture.

6. The process of nitrating sucrose which comprises adding sucrose to anitration bath comprising sulphuric acid, nitric acid, an alkyl ester ofa monohydroxy aliphatic carboxylic acid, said alkyl group containing notmore than five carbon atoms, and one or more members of the groupconsisting of: methyl nitrate, ethyl nitrate, propyl nitrate, amylnitrate, butyl nitrate, dichlorethyl ether, tetrachlorethane, carbontetrachloride, chloroform, the proportion of alkyl ester of monohydroxyaliphatic carboxylic acid present in the mixture being greater than thatof any member or combination of members of aforesaid group present inthe mixture; separating the nitrated sugar from the spent acid, washingthe nitrated sugar with water and with a weak solution of an alkali, andpurifying the nitrated sugar by extracting from it the alcohol solubleimpurities by washing the crystals with a monohydric aliphatic alcoholcontaining not more than five carbon atoms.

'7. The process of nitrating sucrose which comprises adding about 130parts of a mixture consisting of 60% by weight of a nitrated alkyl esterof a monohydroxy aliphatic carboxylic acid, said alkyl group containingnot more than five carbon atoms, and 40% by weight of one or of acombination of two or more members of the group consisting of: methylnitrate, ethyl nitrate, propyl nitrate, amyl nitrate, butyl nitrate,dichlorethyl ether, tetrachlorethane, carbon tetrachloride,

chloroform, to about 1350 parts by weight of a

